As more information emerges about Ian David Long, the 28-year-old alleged gunman who killed 12 at a crowded country bar in Thousand Oaks, California, on Wednesday night, people who knew him have proposed different explanations for when Long became someone capable of committing mass murder.

Police said Long had a history that suggested mental health issues. Ventura County Sheriff Geoff Dean said Thursday that his department had been called to Long’s home in April. Deputies found him acting “irate and irrationally,” according to the Associated Press. A mental health crisis team was then dispatched to Long’s home but concluded he did not need to be taken into custody, Dean said. The other incident in which Long came in contact with the Ventura County Sheriff’s Department listed Long as the victim of assault at a bar.

According to CNN, some of his college friends at California State University–Northridge, where he enrolled using the GI Bill and studied athletic training until he left in 2016, said he did not seem to be a violent man.

But according to the Los Angeles Times, some of Long’s former roommates described him as a quiet person who kept to himself and adhered to routines. One described how he would listen to electronic dance music and dubstep in the sweltering heat, dancing alone. Another roommate said that he had occasionally used the mood-altering drug MDMA and that he took painkillers after a motorcycle accident in 2015 left him with injuries to his hand. According to the roommate, for nine months after the accident, Long mostly stayed in his room, as the accident caused him to have surgeries and left him unable to work. The roommate said Long’s personality changed after the motorcycle accident, making him more isolated.

Others theorized that his experience in the Marine Corps left him with PTSD, which also changed his personality. Long served from 2008–13, according to the AP. During that time, he served one combat tour in Afghanistan, from November 2010 to June 2011. He served as a machine-gunner and earned several awards, reaching the rank of corporal in 2011. According to the New York Times, several members of his former battalion debated whether his problems were rooted in trauma from the military or if they ran back further.

According to CNN, a pastor who served with Long in Afghanistan said Long’s battalion was sent to Afghanistan at a time of intense fighting, but he warned that PTSD does not make a person homicidal, and Long’s behavior should not be blamed on his trauma.

A high school track coach of Long’s in Newbury Park, California, where he grew up, agreed that his behavior had nothing to do with PTSD. According to CBS Los Angeles, the coach said Long assaulted her when he was a senior in high school. The coach, Dominique Colell, said that one day at practice during an argument over a lost cellphone he started screaming at her and grabbing her. “He groped my stomach,” she told the station. “He groped my butt. I pushed him off me and said after that, ‘You’re off the team.’ ” Colell said she was persuaded by other coaches and school officials not to report Long.

More information about Long emerged on Thursday and Friday after the shooting. CNN reported Thursday that authorities have found a Facebook post they believe the shooter wrote around the time of the attack. In the post, the writer says: “I hope people call me insane … wouldn’t that just be a big ball of irony? Yeah.. I’m insane, but the only thing you people do after these shootings is ‘hopes and prayers’.. or ‘keep you in my thoughts’ … every time … and wonder why these keep happening … ”

More biographical information also surfaced. During his Marine Corps service, Long married in 2009 in Honolulu but separated from his wife in 2011, then dissolved the marriage in 2013, according to CNN. He then attended college, and he left after he realized it “wasn’t the job for me,” as he wrote online at the time. He also attended the College of the Canyons for two spring semesters. After he left his home in Reseda while attending college, he moved in with his mother. A neighbor told CNN that Long’s mother “lived in fear” of what her son might do but did not worry about her own safety. He was still living with her at the time of the shooting.

Reporters also learned more information about Long’s history with Borderline Bar & Grill, the site of the shooting. One roommate said Long occasionally went to Borderline but that he didn’t care much for the bar, as he wasn’t “a country guy,” according to the Times. But according to CNN, another one of Long’s friends said Long “really liked it” and would “drag [her] there.” The unnamed friend told CNN that Long had found “a community” at the bar of the kinds of people who would line dance while wearing cowboy boots and hats “in the middle of the suburbs.”

Long was reported to have arrived at the Western-themed Borderline bar and started firing into the crowd at around 11:20 p.m. local time Wednesday. He reportedly shot employees at the front of the bar before setting off a smoke bomb and firing into the crowd. He is believed to have killed himself, police said.

According to CNN, he had entered the bar wearing black and glasses, and he was carrying a Glock .45-caliber handgun with an extended magazine that allowed him to fire more rounds than the gun normally allows. According to BuzzFeed News, even though he obtained the gun legally, the high-capacity magazine he used would have been illegal under California law—if the National Rifle Association and other gun advocates had not used a lawsuit to block the law from being implemented. Witnesses described the gunman as a tall white man.

Authorities have not yet identified a possible motive.

Update, Nov. 8, 2018, at 12:30 p.m.: This post has been updated with information about the suspect’s time serving in the Marines and attending a university.

Update, Nov. 8, 2018, at 5:50 p.m.: This post has been updated with information about the suspect’s behavior while living with roommates and information about the suspect’s college education.

Update, Nov. 9, 2018, at 12:15 p.m.: This post has been updated with information from Long’s college friends; information about the intensity of his experience in the Marines; the allegation from his former track coach that he had assaulted her; information about a Facebook post authorities believe he wrote; information about the extended magazine he used; and general biographical information.